Imaging devices capable of converting an optical image of a subject into an electrical image signal and outputting this signal have rapidly gained popularity in recent years. An example of such an imaging device is a digital still camera. One of the features of a digital still camera is that the user can capture an image while looking at an image display device (such as a liquid crystal monitor for image display), allowing the user to check the captured image right away.
The image captured with a digital still camera will vary with the imaging conditions. For instance, the subject field depth varies with the aperture value, and it is possible to vary with the blurring of the background of the subject, which is in focus. As a method for checking the change in a captured image, there has been proposed an imaging device with which an image signal captured with an open aperture and an image signal captured with a set aperture value are stored, part of one image is replaced with the other image, and this combination is displayed on a display device (see Patent Citation 1, for example).
Patent Citation 1: Japanese Laid-Open Patent Application 2000-125153
Patent Citation 2: Japanese Laid-Open Patent Application 2006-23686
Patent Citation 3: Japanese Laid-Open Patent Application 2003-186461